Considerable efforts have focused on the treatment or prevention of unintended or illicit use of a poison or a pharmaceutically active agent. For example, one treatment for a patient who ingests an excess of a drug or a poison involves administration of an adsorbent such as activated charcoal (see Remington's: The Science and Practice of Pharmacy 1238 (20th ed. 2000)). The activated charcoal is intended to adsorb a portion of the drug or poison and prevent it from entering the circulatory system.
U.S. Pat. No. 4,594,249 to Proctor et al. discloses a method for alleviating the aftereffects of the consumption of alcoholic beverages by administration of activated charcoal to the alcohol consumer immediately before, during or immediately after alcohol consumption.
U.S. Pat. No. 4,761,284 to Nishimura discloses a pharmaceutical composition comprising spherical particles of activated charcoal purportedly useful for adsorbing exogeneous or endogeneous toxins in the gastrointestinal tract of a patient without disintegration of the pharmaceutical composition.
U.S. Patent Application Publication No. 2002/0155103 A1 discloses a composition comprising activated charcoal and limestone allegedly useful for preventing or delaying the onset of aftereffects associated with alcohol consumption.
There have also been attempts in the art to increase the tamper resistance of dosage forms, such as opioid analgesic dosage forms. Prior approaches to developing tamper resistant opioid dosage forms have included combining an opioid agonist with an opioid antagonist. Particular examples of such combinations include compositions including methadone and naloxone (U.S. Pat. No. 3,773,955 to Pachter et al.); methadol or acetyl methadol and naloxone (U.S. Pat. No. 3,966,940 to Pachter et al.); oxycodone and naloxone (U.S. Pat. No. 4,457,933 to Gordon et al.); and buprenorphine and naloxone (U.S. Pat. No. 4,582,835 to Lewis et al.).
U.S. Pat. No. 6,228,863 to Palermo et al. discloses an oral dosage form which combines an opioid agonist and an opioid antagonist such that at least two separation steps are required to isolate the agonist.
U.S. Pat. No. 5,610,193 to Al-Razzak et al. discloses a pharmaceutical composition comprising a pharmaceutically acceptable HIV protease inhibitor and solvent adsorbed onto a pharmaceutically acceptable adsorbent. The reference alleges that the composition provides improved oral bioavailability of the active compound that is poorly water soluble.
U.S. Pat. No. 6,696,088 B2 to Oshlack et al., and U.S. Patent Application Publication Nos. 2003/00073717 A1, 2003/0004177 A1 and 2003/0065002 A1 disclose oral dosage forms comprising an opioid agonist in releasable form and an opioid antagonist which is substantially not released when the dosage form is administered intact.
There remains a need in the art for improved tamper resistant dosage forms and improved techniques for their preparation.